You can slide down a little path between the rocks to avoid falling damage.
You must go to the top of the mountain and then use + to scan for the bone that is 1 “floor” below on a rock plateau (facing the river). There’s a mountain west of Kamassa River. These bones are very small and hard to see so use + to highlight them when nearby.
In front of a hut (south-east of it), in the grass.